Muffler for pneumatically powered tools



April 23, 1968 c. SKQWRON 3,379,278

MUFFLER FOR PNEUMATICALLY POWERED TOOLS Filed Jan. 19, 1967 INVENTOR.CARL SKOWRON ATTORNEY United States Patent 3,379,278 MUFFLER FORPNEUMATIQALLY POWERED TOOLS Carl Sltowron, M. C. #1, Damascus Road,Salem, Uhio 4446i) Filed Jan. 19, 1967, Ser. No. 610,263 4 Claims. (Cl.181-36) ABSTRACT OF THE DISCLOSURE This disclosure relates to a sounddeadening device for use on a pneumatic tool such as a grinder. Anopen-ended sleeve of an elastic, resilient material is tightly fittedover the body portion and exhaust ports of the tool, being bonded to thebody portion. Spent air exhausted from the tool forces the sleeve awayfrom the tool and escapes at the end of the sleeve. A band ofnon-elastic material is placed around the body of the tool closelyadjacent the exhaust ports in the opposite direction from the end of thesleeve through which the air escapes. This band is secured to the sleeveand prevents air from forcing the sleeve away from the body portion ofthe tool.

Pneumatic grinders used in many industrial operations are supplied withcompressed air at approximately 120 p.s.i. through conduits from acompressor. The air is discharged from the grinder through ports in thebody of the tool and the escaping air generates a high pitched whinewhich may reach a level in excess of 160 decibels. Noises at this levelare sufficient to cause damage to the human ear and may cause deafness.If several pneumatic tools are operated in the same enclosed area, theresulting noise produces unpleasant working conditions and impairs theefficiency of those working in the area. The compressed air used topower these tools may carry oil mist from the compressor and the tooland, especially in humid conditions, large quantities of water vapor.These vapors and mists are discharged along with the spent air and arefrequently sprayed on the tool operator. When the compressed air expandsupon discharge from the tool it absorbs heat from the body of the tooland, thus, the tool is unpleasantly cold to the touch. Previouslyproposed mulilers designed to overcome these problems have been ofcomplex construction and their use makes the tool awkward to handle andoperate.

It is the primary object of my invention to provide a noise muiilingdevice for use on a pneumatically powered tool which dampens the noisegenerated by the discharging of spent air from the tool. Another objectof the invention is the provision of such a device which directs thespent air away from the operator protecting him from the vapors andmists carried by the air. A further object of the invention is theprovision of a noise muflling device which provides a comfortablegripping surface for the operator. It is also an object of the inventionto provide such a device which is of simple construction, is easilyinstalled, and which may be used with existing pneumatic equipmentwithout the necessity of altering such equipment.

The above and other objects and advantages of the invention will becomeapparent upon consideration of the following specification and theaccompanying drawing wherein are shown preferred embodiments of theinvention.

In the drawing:

FIGURE 1 is a side elevational view, partially in section, of apneumatic grinder equipped with the device of my invention;

FIGURES 2 and 3 are views similar to FIGURE 1 but showing modified formsof the muffler of the invention; and

FIGURE 4 is an end view of the tool and muffler of FIGURE 3.

The air operated grinder to which the silencing device of the inventionis applied has a cylindrical body portion 11 which houses the air-drivenrotor. A grinding stone or wheel 12 is mounted on shaft 13 which is anextension of the shaft of the rotor. Compressed air is admitted to thetool through fitting 14, controlled by valve 15, passes the rotor andexhausts through ports 16 of collector ring 17. It is this exhausting ofthe spent air through ports 16 that produces the offensive, undesirablenoise. To reduce the level of noise produced and to direct the escapingair away from the operator, I provide a tubular sleeve 18 of resilient,elastic material having reenforcing end ribs 19 and 20 which tightlyfits about the body portion 11 of the tool and extends beyond thecollector ring 17, being tightly fitted to both the body portion 11 andthe collector ring 17 as well as the end portion 21 of the tool. The airexhausted through ports 16 forces the portion of sleeve 18 from thecollector ring 17 to the end of the tool body 21 outwardly and escapesat the end of the sleeve 18. The resiliency of sleeve 18 absorbs a portion of the noise produced by the escaping air and, thus, reduces thelevel of noise produced. In order to firmly secure the sleeve 13, thatportion which surrounds the body portion 11 of the tool is bondedthereto and a band 22 of non-elastic material is placed tightly aroundthe portion of the sleeve covering the body portion 11 closely adjacentthe collector ring 1"]. The band 22 prevents the bonded joint betweensleeve 18 and body portion 11 from being forced apart by compressed airbacking up from the exhaust ports 16. It will also be apparent that thespent air is now discharged toward the grinding wheel 12 rather thantoward the operator thus protecting him from the water vapors and oilmists which may be carried by the air. As the resilient, elastic rubberor synthetic polymer material of which sleeve 18 is made is inherentlyinsulating, the portion of the sleeve secured to the body portion 11 ofthe tool provides a gripping surface for the operators hand which doesnot become cold to the touch even when the body 11 is cooled by theescaping air.

In the modification shown in FIGURE 2, a strip of resilient material 23is spirally wound about a portion of the body 11, the collector ring 17,and the end portion 21, the overlapped portions of strip 23 being bondedtogether. A tubular sleeve 24, similar to sleeve 18, fits over the endof band 23 and is bonded to the cylindrical body 11 of the tool. Thestrip may be wound with successively less tension toward the end portion21 providing a low resistance path for the escaping air. In thisembodiment only that portion of the mufiling device which becomes wornor damaged need be replaced. If, for example, the strip 23 becomes worn,it may be replaced by a new wrapping while sleeve 24 is reused.

When it is desirable to reduce the back pressure of the exhausted airwhile yet mufiling the noise and directing the discharge of spent airaway from the operator, the embodiment of the invention shown in FIGURES3 and 4 may be used. A sleeve 25 is fitted over and bonded to bodyportion 11 and is provided with a restraining band 26 similar to band22. The portion 27 of sleeve 25 overlying collector ring 17 is spacedtherefrom providing an annular chamber 28 into which the spent air isexhausted. Extending longitudinally from sleeve portion 27 is adouble-walled portion 29, the inner wall 39 of which tightly surroundsend portion 21 of the tool and the outer wall 31 of which is spaced frominner wall 30 providing an annular passage 32 open to chamber 28. Theends of walls 39 and 31 are joined by a ring-like member 33 having aplurality of holes 34. Air discharged into chamber 28 moves throughpassage 32 and exhausts through holes 34-.

it will now be apparent that I have invented a muffler for pneumatictool-s which is characterized by its simplicity and which is capable ofsubstantially reducing the level of noise produced by the discharge ofspent air from the tool. In addition the device herein describedprovides a comfortable gripping surface for the operator and pro tectshim from the discharged air.

It should also be apparent that changes may be made in and to the deviceof my invention without departing from the spirit thereof. For example,the restraining band 22 may be secured to the inner rather than theouter surface of sleeve 18. It is also conceivable that, rather thanusing a tubular sleeve, the mufiier could be formed of a length ofresilient, elastic material tightly wrapped about the tool, bonded tobody portion 11 and the overlapped portion of the wrapping bondedtogether. This method of fabricating the muffler has the advantage ofbeing readily adaptable to pneumatic tools of different sizes. For anunderstanding of the true scope of my invention reference should be hadto the accompanying claims.

Having described my invention what I claim is:

1. A cover providing a gripping surface and rnuflier for a pneumaticallypowered tool having a generally cylindrical body portion housing anair-driven rot-or, a connection to a source of compressed air at one endof said body portion, a second cylindrical portion of lesser diameterthan said body portion extending therefrom at the opposite end from saidconnection and having ports for discharging spent air from said tool, athird cylindrical portion extending from said second cylindricalportion, and an output shaft driven by said rotor and journaled in saidthird portion, comprising: an open-ended tubular sleeve of resilientmaterial encompassing said body portion and said second and thirdportions of said tool and bonded to said tool along the portion of saidsleeve extending from the end of said sleeve adjacent said connection toa compressed air source to said exhaust ports, the remaining portion ofsaid sleeve being in close fitting engagement with the adjacent portionsof said tool but not bonded thereto; the arrangement being such thatspent air discharged from said ports passes between said sleeve and saidsecond and third portions of said tool and is discharged to theatmosphere at the end of said sleeve adjacent the outer end of saidthird portion of said tool While that part of said sleeve overlying saidbody portion remains in tight fitting relation thereto.

2. A device according to claim 1 further including a band of non-elasticmaterial surrounding said body portion of said tool closely adjacentsaid second portion of said tool and rigidly bonded to said sleeve.

3. A cover according to claim 1 further characterized in that saidsleeve is comprised of a strip of resilient material wound in spiral,overlapped relationship about a part of said body portion and about saidsecond and third portions, the overlapped portions of said strip beingbonded together and the portion of said strip wrapped about said bodyportion being bonded thereto; and a resilient tubular sleeve surroundingsaid body portion and the portion of said strip wrapped about said bodyportion of said tool and bonded to said body portion and to saidlast-mentioned portion of said strip.

4. A cover according to claim 1 further characterized in that saidsleeve is comprised of a length of tubing of resilient material bondedto the body portion of said tool and extending in spaced relationshipabout said second and third portions of said tool; a second length oftubing of resilient material fitting tightly about said third portion ofsaid tool; and a ring-like member connecting the ends of said tubinglengths and having a plurality of holes communicating with the annularspace between said tubular lengths; the arrangement being such that airexhausted through said ports flows through the annular chamber betweensaid first length of tubing and said second portion of said tool, thenthrough said annular space "between said tubular lengths and isdischarged through said holes in said ring-like member.

References Cited UNITED STATES PATENTS 1,115,704- I l/1914 Manes 181-362,789,652 4/1957 Fannen 181-36 2,949,975 8/1960 Plummer 181-36 3,202,2398/1965 Clarke 181-36 3,225,861 12/1965 Reynolds 181-36 FOREIGN PATENTS496,454 '1 1 1938 Great Britain.- 1,805 3/1964 Great Britain.

ROBERT S. WARD, JR., Primary Examiner.-

